This old Lennox furnace has no c terminal. I can run a wire directly from the furnace to the thermostat. Question is, which terminal do I hook it to? s2

  • Look more widely, it may not be in the usual group of terminals, since traditional thermostats did not need it. Is there a transformer in the furnace somewhere? – Harper Dec 30 '18 at 3:12
  • Can you post the wiring diagram for the furnace and/or photos of the wiring at the furnace? – ThreePhaseEel Dec 30 '18 at 3:16

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